Soil is perhaps the most important natural resource in Oklahoma.  It is important to all, for without soil there would be no life on Earth.  Our food and much of our clothing and shelter come from the soil.  Soil supports the gigantic agricultural system which is the major contributor to the state’s development and continued prosperity.   Oklahoma has a land area of over 44 million acres, part of which is covered by water.  The majority, some 41 million acres, is used for production of food and fiber.  This land has an average value of over $400 per acre or a total value in excess of $16.4 billion, an asset well worth protecting.   Many different kinds of soil occupy this land area.  Some soils are extremely productive while others are not so productive.  Each soil has a set of unique characteristics which distinguishes it from other soils.  These characteristics determine the potential productivity of the soil.   Soil productivity is a result of how well the soil is able to receive and store moisture and nutrients as well as providing a desirable environment for all plant root functions.

Soil fertility is the soil’s ability to provide essential plant nutrients in adequate amounts and proper proportions to sustain plant growth.  These nutrients and their functions are covered in details in the next chapter.  Soil fertility is a component of soil productivity that is quite variable and strongly influenced by management.  Other components of soil productivity, especially soil slope and soil depth, will be the same year after year.  Together with climate, these components set the soil productivity limits, above which yields cannot be obtained even with ideal use of fertilizer.  It is important to realize this and understand that added fertilizer cannot compensate for a soil that is unproductive because it is excessively stony or has a subsoil layer that restricts normal root growth and development.

Link to the old Course Website. 
http://SOIL4234.okstate.edu